Ridler, R. G. 1. (1976). Changing resource problems of the Fourth World. Resources for the Future.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रRidler, Ronald Gene 1931. Changing Resource Problems of the Fourth World. Washington, D.C: Resources for the Future, 1976.
एमएलए (9वां संस्करण) प्रशस्ति पत्रRidler, Ronald Gene 1931. Changing Resource Problems of the Fourth World. Resources for the Future, 1976.
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